"substance for destroying pests, especially insects infesting gardens, homes, or crops," 1939, from English pest + Latinate -cide "killer."
Entries linking to pesticide
pest n.
1550s (in imprecations, "a pest upon ____," etc.), "plague, pestilence, epidemic disease," from French peste (1530s), from Latin pestis "deadly contagious disease; a curse, bane," a word of uncertain origin. Meaning "any noxious, destructive, or troublesome person or thing" is attested by c. 1600. Pest-house "hospital for persons suffering from infectious diseases" is from 1610s.
-cide
word-forming element meaning "killer," from French -cide, from Latin -cida "cutter, killer, slayer," from -cidere, combining form of caedere "to strike down, chop, beat, hew, fell, slay," from Proto-Italic *kaid-o-, from PIE root *kae-id- "to strike." For Latin vowel change, see acquisition. The element also can represent "killing," from French -cide, from Latin -cidium "a cutting, a killing."
*kae-id-
*kaə-id-, Proto-Indo-European root meaning "to strike."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit skhidati "beats, tears;" Latin caedere "to strike down, fell, slay;" Lithuanian kaišti "shave;" Armenian xait'em "to stab;" Albanian qeth "to shave;" Middle Dutch heien "to drive piles," Old High German heia "wooden hammer," German heien "beat."